Hi,
In thinking about it farther,
If you neck the basic case up, it would lower the window. and, if you neck it down, it would raise the window. So, if you neck a 30-06 down to say, .270, it would be most accurate at about 2900 fps. That would make a 25-06 accurate at about 3000 fps. That would continue to the point that it becomes so overbore as to be impracticle.
Does this make sense to anyone?

Incidentally, you guys can edit your poorly spelled words (just like I do) by clicking on the little icon above your post---the one with the pencil symbol. That way no one knows you got it wrong the first time you tiped it.